Well, it's been a while since I took high school classes so I don't know how much the California high school system has changed since I graduated, but I would recommend the following (from most important to least important):

AP biology
AP physics
AP chemistry, if your school has it (mine didn't)
AP math
Geology, if your school has it (I got lucky; mine did, but I took it the last year it was given)
AP English

The AP biology is the only really critical one. The physics, chemistry, etc. will be really convenient, but aren't strictly necessary. What they'll let you do is either (1) test out of courses that you'd otherwise have to take in college and would fill up your schedule, or (2) prepare you for more advanced college-level courses in those subjects if you want to get a broader understanding of science to help support your interest in biology (this is what I did). The English is there on that list because you're going to need to learn how to write and you may as well start now, but you CAN deal with it later or not at all if you can learn to write without it if necessary (I had that in my high school; some courses conflicted with others).

I was very similar to you in high school, except that I was going into paleontology as well as marine biology (now I'm working on fossil plants - go figure). For this reason, geology and physics were more important for me than they probably will be for you, but I'd still recommend getting some geology/paleontology in there if you can. It will be really useful to you later in your career (not to mention just plain fun) to be able to consider the different kinds of marine ecosystems that existed in the past and how they are similar (and not so similar) to their modern counterparts.

By the way, when it comes time to apply for schools, I'd tell you to aim for one of the coastal University of California schools, either San Diego, Santa Barbara, or Santa Cruz. CSU Humboldt and San Diego are also good. If you're looking to go out-of-state instead, I'd look at the University of Washington in Seattle, too, or maybe the University of Florida in Gainesville. Don't trouble yourself with the big-name schools like the Ivys; in marine biology, *these* are the big-name schools.

In college you will likely have to take some chemistry, biology, math and possibly statistics and physics for a marine biology major. So in high school I would take these types of classes so that you can get into more advanced classes once you enter college rather than having to begin in all the introductory classes or having learning everything from scratch.

Thank you for the question and I am glad you have found something you are passionate in. Some classes that will help prepare you for marine biology will be biology, chemistry, physics, maybe some environmental sciences, and a of course math would help too. Any classes in those areas will be of much help. I would also like to suggest something to you; if you have time, try and take a class at the nearby community college. If you fulfill the requirements to be in that class, you can take it at a much lower cost than you would at a college later on depending on where you go, and the credits may also transfer meaning you won't have to take those classes later! It will also look very good and put you ahead of classes as you may even be able to take upper division courses later on when you go to college. Another thing that might help would be go and volunteer in areas that may be related to marine biology, go check out your local college or university and see if they have volunteering opportunities for that kind of thing, maybe even museums or zoos too. I hope it all goes well!

Deciding to major in a biology related subject in college is a very important decision mostly because of the competition, course load, and rigor that is associated with it no matter what school you go to. You have to know that you for sure want to do it so you can excel. In high school, I would strongly recommend AP Biology and AP Chemistry to help you prepare for certain major requirements when you get to college. They will also show you what is expected of you in the field. You should also volunteer and look for internships in Marine Biology to gain more experience and make sure you really want to do it! Good luck!